Selecting optimal conditions for the turbine warm and hot start-up

The changing role of coal-fired power units which are now used more and more often as sources balancing the demand for electricity in the power system calls for a change in the character of their operation. They have to be able to respond appropriately to rapid and substantial variations in loads and they must have the capacity for shortening the start-up time, especially after a few or several hours of downtime. The paper presents an analysis of changes in thermal states in the turbine main elements after short downtime periods and shows the possibilities and consequences of the turbine fast start-up from such states. Optimal warm and hot start-up characteristics are developed. Detailed deliberations are devoted to elements of200 MW turbines, most of which are and will be used as flexible sources of electricity generation in the power system.